Telephone repeater circuits



Aug. 5 1924. i

H. NYQUIST TELEPHONE REPEATER CIRCUITS F" ,ed Sept. 1921 2 Shees-Sheet l Afe ATTORNEY 5 H 3 1l t n, 0 m 5, R. HA an. m LnNn; m WQ W A l Hf N V w Mv/ B Rm 1.4 THQ 6K1. im www2 1H Nww RS Hd Ne Ol Hi Pn? E L E T Patented Ana., ti, leli.

Spilltll HARRY NYQUXST, 0F 'ELMHUBSR NEW YORK, ASSIGNGR A'E0 AEERCAET TELEPHGNE AND TELEGBAEH CHANY, A CORPORTI'N lt" NEW YORK.

TELEPHNE REPEATER CIRCUITS.

Application filed. September 2, 1921. Serial No. @97,84%

T 0 @il whom t may comem:

Be it known that "i, HARRY NYQUIST, residing at Elmhurst, in the county of Queens and State of New York, have invented certain Improvements in. llelephone Repeater Circuits, of which the following is a specification.

This invention relates to telephone rcpeater circuits and in particular to the type commonly known as the 22 type repeater,

in which two repeater elementsv are used ishing the energy losses ordinarily occurring in repeater circuits. More specifically l accomplish theseV variousA objects by the suitable use. of asymmetrical hybrid coil arrangements, designed to give increased transmission eiiiciency between the outI ut of the repeating element and the line at t .e expense of the transmission eliiciency between the -input of the repeating element and the line. The invention will be better understood by reference to the accompanying drawing in which Figure l shows a circuit arrangement as adapted to the usual 22 type repeater circuit. Fig. 2 shows a modification or" the circuit in Fig. l, for use in such cases Where it may be desirable to terminate the telegraph circuits at the repeater station or to have the telegraph signals shunted around said re peater Without .the use of composite sets. Fig. lshows an adaption'of the invention to a founwfe circuit., Figsze to 7 show the invention` as applied to other types or" repeating coils.

Referring more particularly to Fig. l, il and 12 represent transmission lines which. areto be associated with each other at repeater station by the so-called 22 type circuit. This circuit contains a hybrid coil 14, comprising the windings 2li and 25 in series and connecting the line 1l to a balancing network' 15 and the windings 26 and 9.7 inductivelyconnected to 2li and 25. A similar hybrid coil 16, comprising series windings 3e and 35, and the line lZ'to the .balancing network 17 and includes the induction windfings 36 and 37. For conversation in one direction there is connected across the inter'-L rnediate points oi the windings 24 and 25 the input of the repeater 2l, the output of which contains the windings 36 and 37 inductively connected with windings 34 andl 35 in the usual way. Similarly for conver lsation' in the opposite direction, there is con 'nected across the intermediate points of the Wndings 34 and 35 of the coil i6, the input of the repeater 23, the output of which is associated with the coil The connection as thus described is put in .this standard arrangement, the balancing networks l5 and i7 are made to 'have the saineiinpedance as their corresponding lines l1 'and l2, and under these conditions, a portionv of the incoming energy from the line 11 is dissipated in the network l5. and a half only oi" the po-- tential is available for the input of the repeater element 2l. Qi' the amplified energy from output circuit ot 23, hal-l is trans mitted to the line 11 and the other halt is dissipated in the networlrfi.

ln order to increase theelliective capacity of the repeater element, l. propose to' decrease the portion oi? the output energy from the repeater element nwhich is dissipated in the balancing netvvorl: and l accomplish this by making the hybrid coils asymmetric. For example, as shown in i, l make the nun'iloer of turns ci thewinding 25 a frac-v tional part only of those in the Winding 24:, yillus, if there are N turns in the portion ol' the coil 24 associated with the line, l would then make the number of turns in the por- \tion 25 associated with the balancing netequal to Where-Z is the impedance oi the line as seen .from the hybrid coil.l A similar arrangement is provided 1n connection with ythe line l2 and its hybrid coil.

Under these circumstances it is seen that.

a current in the windingr 26, 27 will induce in the Winding 25 an E. M. F. which is only1 of that in Winding 24 although the cur be the same and that therefore the energy` dissipated in l5 Will he only of that sent to the line 11. As e result for a given energyV supplied by element 28 a larger quantity is sent to line 11. lt is also true that the eit'ectivevoltage impressed on the input of element 21 is reduced by the Yfactor m, but this can very readily be made up, in Whole or in part, by means of the potentiometerQl which is always associated Vith repeaters as used in practice. lt will ingeneral still be desireble to arrange the number of turns in the respective parts of the hybrid coil 141 so that the impedance esseen from the output terminals of thel repeater element will be the same as formerly, which will be the internal impedance of the repeater element itself. rl`his will necessitate a change in the 'number of turns in. the windings 2.6 and 27, the change beine` in accordance with the change in the windings 24 and 25. A. sim1- lar line of reasoning applies to line 12, net- Work 17 and coil 16. From the above it is apparent that tlie.circuit arrangement described will either yincite it possible to carry a given amount or power with a repeater element of similar capas-.city or to increase the edective capacity ci' `a tube of given size.

Fige shows a modification in which the number of turns of the winding 25 associated with the balancing network is increased by the factor fm., and the impedance 'of the balancing networks is increased by the saine factor.

ln this case in order to accomplish the desired results it will be necessary to fece the repeater element in the reverseadirection so that the input is inductivel associated with. the line b the Wind Y Y ings 26, il? and the output is couductively associated with 'the windings 24 and 25 ut their intermediate points.

y By asimilar line of reasoning itmay be shown that e similar gainis obtained. For example, incoming energy on the line 1l will new produce in the windings' 26, 27 a voltage lese than normal due to the fact recense former. On the other hand, output energy from the element 21 will be divided between the line 11 and the balancing network 15 in such a Way that the portion dissipated in the network is smaller than that in the line, by the factor m. As a result, for a given effective output to the line 11, a smaller amount of energy must be supplied bythe element 2l or for a given amount of energy from the element 21 a larger quantity will be delivered to the line 11. The new proportion of the number of turns in the hybrid coil and the new impedance ci the balrent flowing in 15 andrin 11, in Series, Wm"i aucing network will still leave the systemA as a Whole balanced in the manner required..

`for a repeater circuit of the 22 type. j

ln this event the arrangement of circuit of i Fig. 2 is especially useful for the reascn that the telegraph impulses, being of a low frequency, are not transmitted ethcicntly by the transformer constituting the hybrid coils7 and therefore substantially no effect is produced by it on the input circuit oi the repeaters. On the other' hand, the impressionoi the full telegraph voltage in the output circuit of the repeater elements, vdocs not produce any appreciable reaction on the line as a whole through the repeater.

Therefore, as indicated in Fig.A 2, the out-- put circuit of the repeater element 2l is con-- ductively connected at the intermediate points of. the hybrid coil land the telegraph j circuit is taken oiii in parallel with said output circuit. lThe branch circuits for this purpose are shown at 31 and 32 and While ict I have shown no apparatus associated there with, it is to be understood that these branches may go directly' or indirectly to suitable telegraph terminal apparatus, or

may be connected together by suitable re` lays to permit the telegraph message to continue through the lines 11 and 12, being shunted around the repeater circuit.

in Figz l have shown the application o my invention. to a our-wire circuit in which thedirection of transmission and the dircction in which the repeater elements operate is shown by the arrows., For the particular direction of operation shown, it is necessary that the balancing network shall have c. larger impedance than the line by the factor m and that the turns oi the hybrid coil direct-ly connected to said network shall have 'previous figures.

amounts to an unlimited extension of the' conductors leerling to the repeater elements ill and .23ct l and 2, as is ivell rinden sto-oel in the art.

lli/'hilo thus l have tlesciihetl the invention in connection with one type of repeater circuit, it should he iincieistootl that it can loe applied equally well to others. ln Fig. l for example there is shown a repeater circuit comprising two coils, and 32', each coil containing three windings 33, 34% ancl.

By melting the windings asymmetrical to the y extent of having m times as many terms in the Winding -/i as in 35, the same asymmetry in (i. trihntion oli power absorption is prooliicefl described in connection with the For this particular connection the balancing network shoiiltll have the same impedance Z as the line. The Wires 36 anti S7 may constitute the four Wiresot a tour-Wire circuit such as shown in Fig. 3 or' may constitute the wires'leatling to repeater elements such. as 2l. and 23 of Figs. lanci 2, the circuit then leading 'to a similar set of coils associated With the transmission line from the other direction. ln either ease these lines 36 anti 3'4" may he spoken of as the four-wire circuit. The arrows indicate the direction or' transmission of talking current. shows the 'conjugate connection for the saine set ot repeating coils, llera again the halanciiwl network has the same imperi'- lance Z as the inconiin2, line ll and the pon-cr consumed in this balancing' network will he a fractional part only or" that which is sent to the transmission line.

Fig. 6 shows the invention applied. to still another type of repeating; coil. ln this type of repeater `one coil comprises the three windings which are shown iii the figure as vertical and a second coil comprises the tivo windings shown as horizontal. symmetry is introcliiceti placing' in one of the vertical coils fm. times as many tiirns as in the other windings ol that coil. ln order to maintain balance for this circuit it is necessary the the balancing net-Work shall have an. impedancel mZ Where Z is the line iinpeance. Under these circun'istances the power consumed in the balancing network will be a fraction only -of that giveirto the line il.

Fig. shows the conjugate connection :for the saine type of repeating coils. 'For this connection it is necessary that the 'balancing network shall have an impedance of and under this condition the repeater will rein-ain balanced and at the saine time the power dissipated in the balancing network A do not wish to be limited to any particular value for the factor lm, it being possible to Vary this over a consinerahle range.

lvlhat is claimed is:

l. ln a repeater circuit comprisingtransmission lines interconnecteii by Oneway repeater paths including amplifiers and having; balancing, networks associated with the lines for ientiering the outgoing sile of one repeater path coniugate with respect to the incomingI side of the opposite repeater path, the method of increasing the effective ca pacity of the aiiipliers, which consists in decreasing the absorption of output ener, y.A

in the balancing network and increasing the ratio of amplification of each amplifier ,to compensate `'for the consequent decrease vin the absorption oy each amplifier of input energy 'from the line. i

2. ln a repeater circuit comprising transmission lines interconnected by Oneway repeater patlis'inch ning amplifiers andL having balancing; networks associated with the lines for rendering' the outgoing siie of one repeater path conjugate vwith respect to the incoming side oi the opposite repeater path, the method of increasing1 the effective ca parity of the amplifiers, which consists in associatinf each transmission line with its eorresponoing balancing network by a coil having asymmetrical windings and'increasthe amplifying ratio of each amplifier to compensate for the consequent decrease in the absorption by each amplifier of input energy from the line.

3. A repeater circiiit comprisin transmission lines, one-Way repeater' pat is inten connecting said lines., amplifiers in each of said paths, a 1oalancing network .for each transmission line, hybrid coils for interconlll() necting the transmission lines, repeater' paths and balancing networks, said hybrid. coils having asymmetrical windings, and;

means *E increasing the amplifying ratioof the amplifiers in the repeater paths to compensate for the decrease in the energy to the amplifier diie to the asymmetric arrangement of the coils.

A repeat-er circuit comprising trans.

mission lines, one-Way repeater paths interconnecting lines',' nrnplers in each of seid perils7 e balancing network for each transmission line, hybrid coils for nccting the; transmission lines, repeater paths sind balancing networks, the windings of seid hybrid coils being designed to treinsfcr loss outpuif-y energy from the amplifiers to the networks then to the lines, and means to increase the amplifying ratio oi the amplifiers to compensate for the corresponding Adecrease in input energy from the line.

5. A., repeater circuit comprising trans mission lines, one-wey repeater paths interconnecting seid lines7 amplifiers in ench oi' scid pathsi n balancing network i'or each transmission. line, hybrid coils for interconnecting the transmission lines, repeater paths ond balancing nctworlrs seid balancing networks being of different impedance from the corresponding lines, whereby the absorption in seid networks oi energy ironi scid lempliiiers is di iinishcd, and ineens for. increasing the snipliiicstion ratio o the amplifiers to compensete 'for the corresponding decrease input energy from che line,

6. A repeater circuit comprising trenemission lines, one-wey repeater paths interconncciin' seid. lissesa eripliiiers in erich of seid perles, o lisis ing neworli "for noch transmission il l g'iirid coiis i'or intercoiiu nec-ting the irene. sion lines, repeater paths 'und lon-leinsing "seid hybrid coils comprising windings condnciirely ccnnected to the lines end i etworlrc, conducsivc connections from intermediari-e points oi' scid windings to the corresponding repeater elements, seid windings lining 'thereby divi-ded into portions having o. retin other thon f unity, and ineens to merecen 'ihn smpliiicstion ratio olf the amplifiers .io compensate for the corresponding decrease .in input energy from. the line.

7. A repeater circuit comprising transmission lines, Oneway repenser paths interconneet-ing scid lines, amplifiers 'in' enclz. oi seid paths, balancingv network jier each transmission line, hybrid coils for interconnect ing the transmission lines, repos/tor pathsand balancing networks, the connecition from esch repeater eieinent to the corre-v sponding hybrid coil vseing such that the ratio of turns directly connected to the.

- transmission line snel directly connected to the balancing network other then unity, and ineens for increasing the simplification ratio oi the empliiiers io compensate for the corresponding decrease in input energy from the line.

8. A repeser circuit. coinpri sing transmission lines, enelway repeater pst-lis internen# nesting seid-lince, cmplilims in each or seid paths, n hslnncing network -,for erich transn mission line, hybrid coils 'for interconnect ing the trenomission lines, repeater paths and balancing notwor is, il'ie connection from iniercors incense ing the transmission lines, repeater paths and balancing networks, conductive connections from theintermediste points of the windings of the hybrid coils to the correspending repeater elements, said connections dividing seid winding into port/ions having a, ratio of turns other than unity, and means for increasing the amplification ratio of the ainpliiiers to compensate :for the corresponding decrease ininput energy from the line.

l0. A repeater circuit comprising trans- .mission lines, onc-way repeater paths interconnecting soid lines, amplifiers in each of said paths, s, balancing network for each transmission line, hybrid coils for interconnecting the ,transmission lines, repeater paths and loslencing networks, conductive connections from intermediate points of the windings ci the hybrid coils to ehe corresponoingrepeeter elements, scid ccnnecw tions dividing said winding into portions iisvinir' e, ratio of turns other than nnity, m0

esch lielsncing network having an impee dence bearing the seme ratio to the impe dence of its line, end ineens for increasing the amplification ratio of the ampliiiers to compensate for the corresponding decrease in input. encgry from the line,

1l. A; repcerer circuit comprisingtrnnsmission lines, Oneway repeater paths interconnecting scid lines, amplifiers in erich of seid paths, n, balancing .network for each transmission line, hybrid coils for interconmeeting the transmission lines, repeater pct s sind balancing net works, conductive connections from intermediate point-s of the series windings of said hybrid coils io the input of the amplifying elements, said connections dividing seid windings into network portions and line poriions in which the ratio oi turnsoif the-network portions and oil' the line portions is less than unity, and ineens :for increasing the amplification ratio of the amplifiers to compensate for the corresponding -ecreose in input energy from the line. .u-

12. A repeater circuit comprising transmission lines, one-way repeater paths interconnecting said lines, amplifiers in each of scid paths, s balancing network for each trainsmission line, hybrid coils for interconnecting the trnnsmission lines,v repeater paths and balancing networks, conductive connections from intermediate oints of the series windings of said hybri coils to the inputs of the corresponding amplifiers, said connections dividing said windings into netlWork portions'and line portions in Which the Tatio of the turns in the network portions and in the line portions is less than unity, each network having an impedance y bearing the same ratio tothe impedance of its corresponding line, and means for increasing the amplification ratio of, the ampliers to compensate for the corresponding derease in input energy from the line.

In testimony whereof, have signed my name to this specification this 29th day of August, 1921.

HARRY NYQUIST. 

